<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
//         function createCounter(num){
//             function fn(a=0){
//                 if(a===0){
//                     num++
//                 return num
//                 }else {
//                     a++
//                     num=a
//                     return num
//                 }           
//             }
//             return fn
//         }
// //实现以下效果
// const counter = createCounter(5);
// console.log(counter()); // 6
// console.log(counter()); // 7
// console.log(counter()); // 8
// console.log(counter(10)); // 11
// console.log(counter()); // 12


function createCounter(initialValue) {
  let count = initialValue;

  return function(resetValue) {
    if (typeof resetValue === 'number') {
      count = resetValue;
      count++
    } else {
      count++;
    }
    return count;
  }
}


//实现以下效果
const counter = createCounter(5);
console.log(counter()); // 6
console.log(counter()); // 7
console.log(counter()); // 8
console.log(counter(10)); // 11
console.log(counter()); // 12
    </script>
</body>
</html>